A sheet processing apparatus executes a post-processing such as sorting and stapling on a sheet-like image receiving medium (hereinafter, referred to as a “sheet”) conveyed from an image forming apparatus. The sheet processing apparatus includes a standby section, a processing section, and a discharge section. The standby section temporarily retains the sheet. The standby section sends the retained sheet to the processing section at a prescribed timing. The processing section executes the post-processing by aligning the sheet received from the standby section. The processing section discharges the sheet subjected to the post-processing to the discharge section.
The processing section executes a stapling processing at a standard position of the sheet. The standard position is located at an inner side with respect to an end of the sheet by a predetermined distance.